package com.strutor.queue;

import com.strutor.linked.BaseLinked;

public class LinkedQueue<E> implements BaseQueue<E> {

    private class Node {
        public E e;
        public Node next;

        public Node(E e, Node next) {
            this.e = e;
            this.next = next;
        }

        public Node() {
            this(null, null);
        }

        public Node(E e) {
            this(e, null);
        }

        @Override
        public String toString() {
            return e.toString();
        }
    }

    private Node head, tail;
    private int size;

    public LinkedQueue() {
        head = null;
        tail = null;
        size = 0;
    }



    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size ==0;
    }

    @Override
    public void enqueue(E e) {
        if (tail == null){
            tail = new Node(e);
            head = tail;
        }else{
            tail.next = new Node(e);
            tail =tail.next;
        }
        size++;
    }

    @Override
    public E dequeue() {
        if (isEmpty()){
            throw new IllegalArgumentException("队列为空，不能出队");
        }
        Node retNode = head;
        head = head.next;
        retNode.next = null;
        if (head == null){
            tail = null;
        }
        size --;
        return retNode.e;
    }

    @Override
    public E getFront() {
        if (isEmpty()){
            throw new IllegalArgumentException("Queue is Empty，can not get");
        }
        return head.e;
    }

    @Override
    public String toString() {
        StringBuilder res= new StringBuilder();
        res.append("Queue :front ");
        Node cur = head;
        while(cur != null){
            res.append(cur + "->");
            cur = cur.next;
        }
        res.append(" NULL tail");
        return res.toString();
    }


    public static void main(String[] args) {

        LinkedQueue<Integer> queue = new LinkedQueue<>();
        for (int i = 0; i < 10; i++) {
            queue.enqueue(i);
            System.out.println(queue);

            if (i % 3 == 2) {
                queue.dequeue();
                System.out.println(queue);
            }
        }
    }
}
